This invention relates generally to a system and method for detection of signal light parameters, and more particularly to a system and method for detecting and reporting railroad signal light status.
Visual railway signals, particularly signal lamps, are important components of a modern railway system and its operation. It is desirable to be able to verify that a signal lamp is in its desired state, illuminated, dark, or flashing, i.e., periodically cycling between illuminated and dark states. It is also desirable to detect and quantify the optical power exiting the signal head. Such optical power can be reduced by several factors including bulb age, dirt on lens or reflector surfaces, and damage to lens. Previous methods monitor the current drawn by a signal lamp to detect loss of filament. Such methods do not provide insight as to the condition of the entire optical system of the signal unit (i.e. lens, reflectors). Newer methods of monitoring flashing warning lights in railroad applications primarily involve incorporating lamp status determination systems positioned at the site of the visual signal lamp that report the determined signal lamp status to a remote monitoring point. These methods are generally labor intensive to install and to calibrate and do not provide a reliable, unambiguous, long-term indication of lamp performance.
These methods have their own inherent inaccuracies and delays and it would be desirable if these inaccuracies and delays are reduced or eliminated. There is therefore need for a system and a method based on transportation of actual light signals from the site of the signal lamp to a remotely located processing and monitoring point to allow more complex, thorough, direct and upgradeable decision logic to be performed.